Control system for circuit breakers



Dec. 2, 1941. DE cRpcE ET AL 2,264,280

CONTROL SYSTEM FOR cmcum BREAKERS Filed July 25, 1939 I v I WITNESSES: INVENTORS Ger-mere De Croce and a lnil/ar l9. .Derr.

Patented Dec. 2, 1941 UNITED STATES PATENT OFFICE CONTROL SYSTEM FOR CIRCUIT BREAKERS Application July 25, 1939, Serial No. 286,347

10 Claims.

initial closure thereof or after the breaker has f been opened by an overload or any other type of line fault to which the circuit breaker has been made responsive, will provide for a predetermined number of successive reclosing operations, after which the breaker will be locked out in an open position.

A more specific object of our invention is to provide a simple and inexpensive relay system for controlling the closing operation of a circuit breaker, the relays of such system being operable in a novel interlocking arrangement, in accordance with successive opening and closing motions of the breaker, whereby the number of closing operations of said breaker are limited to a predetermined number.

A further object of our invention is to provide a control system for a circuit breaker which will limit the breaker closing operations to a predetermined number, and which will automatically reset itself to its initial position when the breaker remains closed for a predetermined time period on any one of the closing operations.

A further object of our invention is to prevent a circuit breaker from pumping in the event that the latching mechanism fails to hold the circuit 1 breaker closed.

These and other objects of our invention will become more apparent from the following description when taken in conjunction with the accompanying drawing, the single figure of which J diagrammatically illustrates a circuit breaker embodying our invention.

Referring to the drawing, the single figure of which illustrates a preferred embodiment of our invention, reference character I designates gen- 1 erally a circuit breaker of any suitable type which may be utilized, for example, to connect a source of power supply 2 and a load 3. The circuit breaker I may be provided with any suitable type of fault-responsive tripping means which are well known in the art. The particular means shown comprises an overload relay 4 which is operatively connected to spring biased latch member 5 which functions to hold the circuit breaker in a closed position under normal load conditions.

The breaker is tripped to an open position under overload conditions by energizing the winding of overload relay 4 from current transformer 6 in a well known manner.

The various electro-responsive devices of our invention may be energized through any suitable source of electric power and in the present embodiment of our invention, the source of power is represented by auxiliary power conductors l8 and [9.

The circuit breaker may also be provided with any suitable type of closing means such as a solenoid operated device 1 having a coil for moving the breaker to a closed position, which may be energized from conductors l8 and I9 of the auxiliary source of power through contact members 8b of control relay 8.

A cut-off relay 9 may also be provided to shunt the winding of the control relay 8, through its contact members 9a, when the circuit breaker has moved to a closed position and is effective to deenergize the closing coil of solenoid l.

The interlocking relay system, in accordance with our invention, comprises relays [0, H, and i2, each of which is provided with a plurality of make and break contact members, as shown, and their operation will be explained in detail hereinafter.

A timing device, such as pendulum relay I3, is also provided for timing the periods when the breaker I is in a closed position.

In the event that the circuit breaker i remains closed on any of its closing strokes beyond the predetermined time interval as measured or determined by the timing relay 13, we have provided a slow drop-out relay [4, the action of which may be retarded by any suitable means such as a dashpot l5, to automatically reset our device to its initial position.

The circuit breaker I may be locked in an open position after it has completed the predetermined number of closing operations which are permitted by our invention by any suitable lock-out means such as lock-out relay [6 which when energized opens the circuit between the control relay 3 and the auxiliary power conductors l8 and I 9.

A hand switch H, or any other well known switching means, may be utilized to initially close the breaker.

So that our invention may be better understood, a detailed description of the operation of the arrangement shown will now be given.

With the breaker in an open position, the winding of the timing relay I3 is energized from conductors l8 and I9 of the auxiliary power supply through a circuit which extends from conductor I9 through conductors 32 and 43, the Winding of timing relay I3, conductors 44 and 45, contact members Ille of relay I0, conductors 46, ll and 48, contact members I2d of relay I2 and conductor 49 to the other conductor I8 of the auxiliary power supply.- When the timing relay I3 is thus energized, its pendulum member I 3b closes contact members I3a. With the breaker in open position the retarded or slow drop-out relay I4 is also energized from the auxiliary power supply through closed contact members I 3a of timing relay I3.

Under normal circuit conditions, when the hand switch IT is closed, the coil of control relay 8 will be energized from conductors I8 and IS of the auxiliary source of power, through a circuit which extends from conductor I8 through conductor 20, hand switch II, conductor 2!, contact members Ilia of relay I6, conductors 22, 23 and-24g-coil of control-relay 8, conductors 25 and 26-, breaker auxiliary r zoiitacl'r members lo, conductors 27-, 28, 29,60; 3| and 32 to conductor I9 of the auxiliary source or power supply.-

When relay 8" is energized, its contact members b are closed and acircuit for energizing the closingcoil of solenoid 'I= is established, which extends from conductor I'B- through conductors 20, 3-3 34 and '35; contact members 82) of control relay 3, conductor 36, the winding of closing coil of solenoid- I and back to the other conductor i9 ofthe auxiliary power source through conductors 31, 28, 29, 3U; 3| and 32 h In order that the circuit breaker may reach its fully closed position and be latched in such position by latch member 5 before the closing coil of solenoid I is deener gized, a holding circuit for keeping the control relay 8- energized until the circuit breaker 'is fully closed is provided through the closure of contact members ea of the control relay.

When the circuit breaker I reaches a fully closed position and is latched inby the latching device 5, cut 'off relay 9' will be energized from the auxiliary power supply conductors I8' and 59 through a circuit which is closed through auxiliary contact members lb on the circuit breaker I. Upon closure of contact members do, the coil of the control relay 8 is shunted through conductors 25', 38, 3 9, 40- and' 24". It will be apparent that when the operating coil of the relay 8 is thus shunted, relay 8 will be deene'rgized and the breaker closing coil of solenoid I will also be de energized since the contact members 8b of the relay 8 will be opened.

Should the latching mechanism 5 fail, for any reason, to latch the breaker in closed position on the initial closing stroke of the breaker, or should the breaker, for any reason, fail to remain closed for the predetermined time interval as determined by the setting of the timing relay I3, the circuit breaker I' will be permitted to make a predetermined number of attempts at reclosure; If the breaker fails to remain closed for the period determined by the setting of timing relay I3 on the last of the predetermined number of closing operations, thelock=out relay l'5'Wl11 be rendered effective to lock the breaker in an open position.

Likewise, should the circuit breaker be operating under normal conditions in a closed position and an overload or some other type of line fault to which the breaker has been made responsive causes the relay 4 to operate and trip the breaker to an open position, our device" will permit the breaker to make a predetermined number of at tempts to reclose itself, after which the breaker will be locked in open position by relay I6.

On the initial or first closing stroke of the breaker, auxiliary contact members Ia of the circuit breaker I are closed and establish a circuit for energizing the winding of relay I!) from the auxiliary power source which extends from conductor I9 of the source through conductors 5B, 5! and 52, the winding of relay I0, conductors 53 and 54, contact members My of relay II, conductors 55 and 55, closed auxiliary contact members Ia of the circuit breaker, conductors 57 and 58, contact members II of relay II and conductor 59 to the other conductor I8 of the auxiliary power source.

It will be apparent that when the winding of relay I0 is thus energized on the closing stroke of the breaker, the timing relay I3 which, as hereinbeiore explained, is energized when the breaker is in an open position, will now be deenergized through the opening of contact members Ille ofrelay Ill. Deenergization of the timing relay I3 causes its pendulum member I3b to vibrate and intermittently open and close its contact members I3a for the predetermined time interval for which the relay I3has been set. The retarded drop-out relay I4 which is energized when contact members I3'a of the timing relay l3 are closed is so constructed, however, that it will remain closed and hence its contact members Ida will remain closed, so long as the vibrating element I312 of the timing relay I3 continues to intermittently open and close its contact members I3a.

If the circuit breaker fails to remain closed for the predetermined time interval as determined by the setting of the timing relay I3, and hence contact members Ma of relay I4 remain closed, the winding ofrelay II will also be energized in series with the already energized winding of relay I0 causing the realy' II to close. The circuit for energizing windings of relays Ill and ii in series from-the auxiliary power source may be traced from conductor I'8 of the source through conductors 20,33 and 6!], closed contact members l ia of relay I 4, conductors 61, 62 and t3, the winding of relay l I, conductors 64 and65, closed contact members lUa of relay Ill, conductor 53, the winding of relay I5! and conductors 52, 5! and 50 back to conductor IQ of the'auxiliary power source.

With both relays I0 and Ii energized, the circuit is again completed from the auxiliary supply source for energizing the winding of the timing relay I3, and may be traced from conductor I3 through conductors 32- and ii-the winding of relay I-3, conductors 44 and 82, contact members I00, conductor 83, contact members IIc, conductors 84 and 48, contact members lid of relay I2, and conductor 49 to conductor I8. Reenergization of the timing relay I 3- places it in readiness to time the period that the breaker remains closed on its second closing operation.

When the circuit breaker I moves to its full open position after its first attempt at closure, control relay 8 is again energized through the closed auxiliary contact members- Ic oi the circuit breaker. With relay 8 in closed position, the closing coil 1 of the breaker isnow energized for the second time in the same manner as hereinbefore described. 7

Upon this second closure of the circuit breaker, the winding of relay I0 is now'shunted out due to the closing of the auxiliary contact members la on the breaker causing relay ID to open. The shunting circuit for the winding of relay l may be traced from one side thereof through condoctors 52 and 65, closed relay contact members lid of relay H, conductors G7 and 51, closed auxiliary contact members la of the circuit breaker, conductors 56 and 68, closed contact members ile of relay il, conductors 69 and 65, closed contact members Illa of relay l0 and con-- ductor 53 to the other side of the winding of relay I0.

As relay [3 now opens, relay i2 is energized from the auxiliary power source through contact members Ha of relay I! and contact members Hid of relay $0. The circuit for thus energizing the winding of relay 12 may be traced from conductor IQ of the power source through conductors 5i] and 70, winding of relay l2, conductors 7i and 12, contact members Ila of relay H, conductor 13, contact members 40d of relay Hi, conductors i i and Bi, contact members Ma of relay I4 and conductors 6%], 33, and 20 back to conductor 3 of th auxiliary power source.

Also when the circuit breaker closes for the second time, the timing relay !3 will be deenergized substantially at the same time that relay HE is shunted to its open position. With the timing relay !3 now deenergized, drop-out relay I i will remain closed for the predetermined time interval for which the timing relay it has been set as heretofore explained.

If the breaker fails to remain closed on its second closing stroke for a period longer than that for which the timing relay !3 has been set, and again moves to an open position, provision is made for effecting a third and final closing operation of the breaker. As the breaker again moves to its open position, relay H will now be deenergized by the opening of auxiliary contact members !a of the breaker. When relay H becomes deenergized and moves to its open position, the energizing circuit for the timing relay I 3 is again established from the auxiliary power source to prepare it for timing the period that the breaker remains closed on its third closing operation. This circuit may be traced from conductor 59 of the auxiliary source through conductors 32 and 43, the winding of relay :3, conductors 44 and 55, relay contact members lee, conductors 45 and 85, relay contact members l in, conductor 83, relay contact members He, and conductor 8? to source conductor !8.

With the breaker now in its open position for the second time and auxiliary contact members 10 on the circuit breaker closed, the control relay 8 is again operated to energize the closing coil of solenoid 1, as hereinbefore described, and the breaker moves to a closed position for the third time. As the breaker reaches its closed position, auxiliary contact members Ia of the breaker are again closed and relay #0 is again energized from the auxiliary source of power in the same manner as it was energized when the breaker auxiliary contact members la were closed on the initial closing stroke of the breaker. With relay H! now energized, the circuit for the timing relay I3 is again opened.

Should the breaker fail to remain closed on its third closing operation for a period longer than that for which the timing of the pendulum relay has been set, our relay system will new function to operate the lockout relay l6 and prevent any further attempts at closing the breaker. As the breaker moves to its open position for the third time, relays II and H) are energized in series from the auxiliary supply conductors i 8 and IS in the same manner as hereinbefore described. At this time, relays H), H and 12 are all energized for the first time and the look-out relay I6 will now be energized from the auxiliary power supply conductors l8 and I9 through the contact members of all three relays. This circuit may be traced from conductor 19 of the source of supply through conductors 32, 34, l5, '16, the winding of lock-out relay l6, conductor T1, closed contact members lflb of relay [0, conductor 78, closed contact members no of relay ll, conductor l9, closed contact members 12b of relay i2, and conductor 88 to the other conductor l8 of the auxiliary supply source.

Once the look-out relay !8 has been operated, the circuit for energizing the control relay 8 is opened through relay contact members 16a of the look-out relay l6, and it will be apparent that such an open circuit will prevent further energization of the closing coil 1 of the circuit breaker I, thereby rendering the closing mechanism of the circuit breaker inefiective for iurther closing operations.

In the foregoing description it has been assumed, for purposes of explanation, that the circuit breaker failed to remain closed for a predetermined time on each of its closing operations. However, should the breaker remain closed for a longer period than that for which the timing relay l3 has been set, on any of its predetermined number of closing strokes, the intermittent operation of contact members 13a of relay i3, as hereinbefore described, will cease and cause contact members 30. to remain open. Contact members i ia of relay I l will then open, since relay !4 is now deenergized because contact members i3a are open, and the relays H], H and l2 will reset themselves to the initial position which they occupied when the hand switch IT was closed to effect the initial closing stroke of the breaker.

This feature of our invention permits the circuit breaker to make two reclosing operations in the event that either a fault occurs subsequently in the latching mechanism for holding the breaker closed, or the breaker is tripped out at some later time because of an overload or because some other type of line fault, to which the circuit breaker has been made responsive, trips the breaker out.

While we have shown and described a system wherein provision is made for limiting the number of successive attempts at reolosure to two, it is to be understood that any desired number of attempts at reolosure may be provided for by utilizing th principle of our invention.

In conclusion, it may be stated that While the foregoing description and diagrammatic illustration constitutes one practical embodiment of our invention, we do not wish to be limited thereby, inasmuch as changes and modifications will be obvious to those skilled in the art, and we desire therefore that only such limitations be placed thereon as ar necessary in th light of prior art.

We claim as our invention:

1. In combination, a circuit breaker, means for closing said breaker, lock-out means to lock said breaker in an open position, and a device for limiting said closing means to a predetermined number of substantially instantaneous closing operations when said breaker does not remain closed for a predetermined time interval on any one of said closing operations, said device comprisingtiming means for measuring said time interval, and a plurality of electro-responsive devices actuated in predetermined sequence in accordance with successive opening and closing operations of said circuit breaker, said electroresponsive devices being operable uponopening of said breaker following the last of said predetermined closing operations of said breaker to render effective said lock-out means.

2. In combination, a circuit breaker, closlng means for said breaker, latching means for holding said breaker closed when said breaker is moved to a closed position, lock-out means to lock said breaker in open position, and means,

operable upon failure of said latching means to hold said breaker closed for a predetermined time interval, to permit said breaker closing means to effect a plurality of successive substantially instantaneous reclosing operations of said breaker, said means comprising means for timing said predetermined time interval, and a first, second and third electro-responsive means actuated in predetermin d sequence in accordance with successive opening and closing operations of said circuit breaker, said electro-responsive means being effective upon opening of said breaker following the last of said predetermined number of reclosing operations of said breaker to render effective said lock-out means.

3. In combination, a circuit breaker, closing means for said reaker, means for opening said circuit breaker in response to predetermined circuit conditions, lock-out means for locking. said breaker in an open position, and means for liniiting said breaker to a predetermined: number of substantially instantaneous closing operations when said breaker does not remain closed for a predetermined time interval upon any of said breaker closing operations comprising timing means operable in response to a closed position of said circuit br aker for timing the period when said breaker is closed, and a plurality of electroresponsive devices arranged for operation in pre determined sequence upon successive opening and closing operations of said breaker, said electro-responsive means being effective upon opening of said breaker following the-last of said predetermined closing operations of said breaker to render said lock-out means effective.

4. In combination, a circuit breaker, closing means for said breaker, lock-out means for looking said breaker in an open position, means for opening said breaker in response to predetermined circuit conditions, and means operable when said breaker is opened for limiting said breaker closing means to a predetermined number of substantially instantaneous reclosing operations when said breaker does not remain closed for a predetermined time interval upon any reclosing operation thereof comprising timing means operable in response to the closed position of said circuit breaker for timing the period of closed position of said breaker, and a system of at least three electro-responsive de vices arranged for operation in predetermined combinations in accordance with successive opening and closing operations of said breaker, said devices being operable upon opening of said breaker following the third closing operation of said breaker to render effective said lock-out means.

5. In combination, a circuit breaker, closing means for said breaker, lock-out means for locking said breaker in an open position, means for opening said breaker in accordance with predetermined circuit conditions, and means operable when said breaker is tripped out by said openingmeans'for effecting two successive substantially instantaneous reclosing operations of said breaker in the-event said breaker does not remain closed for a predetermined period of time upon any reclosing operation thereof, comprising, a timing relay operable in response to a closed position of said circuit breaker for timing said period when said breaker is closed and a system of three electrically-interlocked relays arranged for operation in predetermined sequence upon successive opening and reciosing operations of said breaker, said relays being effective upon opening of said breaker following the'second reclosing operation thereof to render effective said lock-out means.

6, In combination, a circuit breaker, closing means for said breaker, lock-out means for locking said breaker in an open position, means for opening said breaker in accordance with predetermined circuit conditions, and means operable when said breaker is tripped out by said opening means for effecting at least two successive substantially instantaneous breaker reclosing operations in the event said breaker does not remain closed for a predetermined time interval upon any of the said suc essive reclosing operations thereof, comprising at least three electrically-interlocked relays operable in predetermined sequence in accordance with successive opening and reclosing operations of sai breaker, said interlocked relays being effective upon an opening of said breaker following second reclosing' operation of said breaker to render effective said lock-out means, and includ ing timing means operable when the breaker is in closed position, for timing the closed period of said breaker upon each of said reclosing oper ations, and means responsive to said timini means to reset said interlocked relays to thei initial position when said breaker remains closed longer than th said predetermined time interval on any of said reclosing operations thereof.

'7. In combination, a circuit breaker, closing means for said breaker, lock-out means to lock said breaker in an open position, means for opening said breaker in response to predetermined circuit conditions and means operable when said breaker is opened for effecting a predetermined number of substantially instantaneous reclosing operations of said breaker in the event that said breaker does not remain closed for a predetermined time interval on any reclosing operations thereof, comprising a first, second and third relay, energized in predetermined in terlocked arrangement in accordance with successive opening and reclosing operations of said breaker, said relays being simultaneously ene gized upon an opening of said breaker following the second reclosing operation of said breaker to render effective said lock-out means, and including timing means responsive to the closure of the breaker for timing the reclosed period of said breaker upon each of said reclosing operations and means controlled by the said timing means to reset said relays to their initial position when said breaker remains closed for a pe riod longer than said predetermined time inter val on any of said reclosing operations of said breaker.

8. In combination, a circuit breaker, closing means for said breaker, latching, means for bolding said breaker closed when said breaker is moved to a closed position, lock-out means to lock said breaker in an open position, and means operable upon the failure of said latching means to hold said breaker closed for a predetermined time interval on the initial closing operation of said breaker to effect a predetermined number of substantially instantaneous reclosing operations of said breaker comprising a system of at least three relays arranged for operation in predetermined sequence upon successive opening and reclosing operations of said breaker, said relays being effective upon an opening of said breaker following the second reclosing operation of said breaker to render effective said lock-out means and including timing means operable in response to the closure of the breaker for timing said predetermined time intervals and means controlled by said timing means to reset said relay system to its initial condition when said breaker remains closed upon either the first or second reclosing operations thereof.

9. A reclosing device for effecting a plurality of substantially instantaneous reclosing operations of a circuit breaker when the breaker does not remain closed for a preselected time interval on any closing operation thereof comprising, a timer for measuring the closed period of the breaker, means for initiating operation of said timer whenever said breaker is closed, first, second and third control relays, means operable upon the initial closure of the breaker to energize the first relay, means for energizing the second relay and for retaining the first relay energized upon the first opening of the breaker, means for energizing the third relay and for shunting out the first relay upon the first reclosure of the breaker, means for deenergizing the second relay upon the second opening of the breaker, means for reenergizing the first relay upon the second reclosure of the breaker, means for reenergizing the second relay upon the third opening of the breaker, all of said control relays being then energized, lockout means for preventing further reclosing operations of said breaker, and means operable when all of the control relays are energized to actuate said lockout means.

10. A reclosing device for effecting a plurality of substantially instantaneous reclosing operations of a circuit breaker when the breaker does not remain closed for a preselected time interval on any closing operation thereof comprising, a timer for measuring the closed period of the breaker, means for initiating operation of said timer whenever said breaker is closed, first, second and third control relays, means operable upon the initial closure of the breaker to energize the first relay, means for energizing the second relay and for retaining the first relay energized upon the first opening of the breaker, means for energizing th third relay and for shunting out the first relay upon the first reclosure of the breaker, means for deenergizing the second relay upon the second opening of the breaker, means for reenergizing the first relay upon the second reclosure of the breaker, means for reenergizing the second relay upon the third opening of the breaker, all of said control relays being then energized, lockout means for preventing further reclosing operations of said breaker, means operable when all of the control relays are energized to actuate said lockout means, a reset relay operable when deenergized to reset said control relays to their initial position, and means to deenergize said reset relay when the breaker remains closed for a period longer than that for which th timer has been set.

GENNERO DE CROCE. WILLARD A. DERR. 

